Deployment of troops in foreign theatres requires a massive airlift capability. Transport squadrons are called upon to deliver men and materiel, day and night, around the clock, usually during long transmeridian flight. The relentless fatigue encountered in such operations can be severe enough to pose a flight safety hazard. During Operation Alliance, a month long airlift (January 1996) in support of Canadian troops in Bosnia, 18 Air Transport Group CC-130 Hercules carried out 86 missions from Trenton to Split with aircraft landing in theatre every 4 hours. Most crews attained the 120 hour maximum allowable flying time per 30 day period, in as little as 2 weeks. There were several reports of aircrew falling asleep at the controls. After the main airlift was completed, only three of these missions were flown each week. This frequency of re-supply missions was adequate to sustain Canadian troops in former Yugoslavia. Because these sustainment flights were flown in a more relaxed manner, aircrew were given 32 hours on the ground in the United Kingdom on arrival from Trenton, Canada (5 time zones), before proceeding to Zagreb, Croatia (1 time zone), instead of the 14 hours they were given at this stage of the mission, during the original airlift. The current study is an attempt to document to what extent fatigue (and time zone changes of 5 and 6 hours) can impact of aircrew performance during routine re-supply missions. Any fatigue-related lapses in performance in this study, will only worsen when crews are asked to fly repeated missions back-to-back with minimum crew rest between mission legs as was done during operation alliance. Ten routine resupply missions from Trenton to Zagreb were studied and involved 53 aircrew subjects. In order to document their sleep hygiene, the aircrew were asked to were wrist actigraphs from approximately 5 days prior to the mission, until the mission was completed.